In recent years, technology for detecting a state of breathing of an occupant has been developed. Grasping of the state of breathing of an occupant can be applied to various technological fields. For example, in a condition where an occupant is hard to continue a driving operation due to, for example, sudden illness, it is conceivable that a length, a depth, and/or the like of breathing differ from those of breathing in a normal state. In consideration of this, a configuration, which enables detection of the state of breathing of an occupant with sufficient accuracy, would be able to avoid a traffic accident. For example, in a case where an occupant gets difficult to continue a driving operation of a vehicle and on detection of the occupant's state, the driving operation of the occupant may be switched to an automatic control to cause a vehicle to stop its traveling.
For example, Patent Literature 1 proposes a technology to equip a sensor in a belt portion of a seatbelt for detecting a state of breathing of an occupant. In the configuration where the sensor is equipped to the seatbelt, an occupant would be equipped with the sensor simultaneously when the occupant equips the seatbelt. In a configuration where the sensor equipped to the seatbelt is capable of detecting a state of breathing of an occupant, the configuration does not require the occupant an additional and exclusive operation to equip the sensor.